DPS: Must have an AoE, preferably Physical or Dark. Dark magic as Metatron is resistant to everything but Dark, and the Horus in the first two waves is weak to Dark. Physical DPS will get extra turns for the party whenever it crits, which is why AoE w/ acc is recommended to raise the chances of getting a single crit.

Phys Null/Evasion: Treat as a DPS. If Phys Null/Repel/Drain, it will stop the Hanuman/Orochi from using their AoE phys which hurts. If Phys Evasion, it'll lose them turns.

Healer: Must have Mediarama, other slot is for Diarama + Resists. Diarama is used as if you run any Phys Null/Repel/Drain, the enemies will regular attack a target, and the auto AI will heal that targeted ally up.

As for brands:

Speedster - Divine + Ward/Speed (Speed, HP, Phys Evasion)

Magic DPS - Divine + Ward (MATK, HP, Speed, Phys Evasion)

Phys DPS - War + Ward (PATK, ACC)

Healer - Divine + Ward (Recovery, HP, MATK, Speed, Phys Evasion)

Demons:

Fenrir: Speedster for getting your party's battle speed up to the required amount. Makarakarn is required to prevent Titania from wiping your party with magic, and helps reduce the number of turns Metatron gets by repelling Purgatory/Holy Wrath.

Pazuzu: Nulls Force/Dark/Light and heals. The force null loses turns for Hanuman when it uses Mazanma, and Light/Dark Null works wonders against Metatron after it blasts through the first Makarakarn.

Feng Huang: A speedier option than Pazuzu as a healer without any relevant Nulls and low HP. However, it can have way higher evasion + crit resistance which helps if you have trouble with the first two waves.

Pallas Athena: A good Physical DPS that comes with Mana Aid. Basically, a "budget" Yoshitsune.

1st wave - Kill order is Hanuman > Orochi > Horus. Hanuman will start off the fight always with Vorpal Blade (unless you have two nulls/repels/drains), and will start using it if the only one alive. Horus will just spam Diarama for 450, it's not a lot.

2nd wave - If you have Makarakarn or an Elec Null/Drain/Repel, Titania will use Makajamaon. You can exploit that if playing manual - kill order should be Titania > Orochi > Horus.